This invention relates generally to methods and apparatus providing advanced operating features for audio and/or video programs recorded on disk media, for example recordable digital video disks.
Various devices have been developed to enable consumers to record video and audio programs for later presentation. Such devices include tape recorders, video cassette recorders, recordable compact disks, and most recently, recordable digital video disks (DVD). A DVD that can be recorded on only once, and thereafter is essentially a DVD read only memory, is referred to by the acronym DVD-R. The acronym DVD-R is also used generally to refer to the write-once, or record-once, technology. Several formats are available for DVD's to be recorded on, erased and re-recorded, that is overwritten or rewritten. These are referred to by the acronyms DVD-RAM, DVD-RW and DVD+RW. As of this time no uniform industry standard has been adopted. The acronyms DVD-RAM, DVD-RW and DVD+RW are also used generally to refer to the respective rewritable technology. Reference herein to rewritable DVD technology, devices and methods is generally intended to encompass all of the standards which are now being used, as well as those which may be developed in the future.
In many cases, the program presentations are recorded in the viewer and/or listener's absence, for presentation at a later, more convenient time. This is referred to as time shifting the program. At other times, a program is being viewed and/or listened to without being recorded, and with out any interest in a recording, but the viewer's and/or listener's attention is interrupted, for example by a telephone call or an unexpected visitor. If the viewer and/or listener is watching a television program, for example, and has a cassette tape in a VCR, or can retrieve and load such a cassette tape quickly, the program can be recorded. However, the viewer and/or listener cannot view and/or listen to the program in its entirety, and in a proper time sequence, until after the recording has been completed. The time to completion of the recording can be short or long, depending on the length of the program.
A desirable feature in a DVD device would enable a viewer and/or listener to initiate resumption of the program presentation as soon as the interruption or pause has ended, without sacrificing the program content during the interruption or pause.
Although rewritable DVD technology is generally available, operation is limited to such basic functions as play, record, fast forward reverse and stop. Pause is available, but only as a counterpart to pause operation in a VCR, for example interrupting the play back of a prerecorded program or interrupting the recording of a viewed program to eliminate commercials from the recording. Unlike computer hard drives, recordable DVD devices have a very significant additional function, which is playing back prerecorded DVD's. Thus, there is an economic incentive to develop rewritable DVD technology, including methods and devices, that can be used instead of a computer hard drive. It is a challenge to provide such devices with improved, advantageous features without compromising the goal of decreasing costs and increasing sales. Such novel DVD features should include the ability to simultaneously view and record on a disk medium in a seamless fashion, without the high operating speed of a computer hard drive. A recordable DVD device with a single head for reading and writing cannot read and write simultaneously. Accordingly, the terms seamless and simultaneous are used herein to denote that recording and playing back program material in accordance with the inventive arrangements has the appearance of being simultaneous to the viewer and/or listener, even though the functionality is actually alternating or multiplexed.
A basic rewritable DVD device, having for example a 1× (one times) read and a 1× (one times) write capability, typically has maximum data rates for recording or playing back of only approximately 11 megabits/second.
A system for implementing a single pause in such a basic rewritable DVD device is described in copending, co-owned U.S. application Ser. No. 09/433,434, filed Mar. 31, 1999, now U.S. Pat. No. 6,173,115. Multiple pauses are even more problematic. Multiple pauses can result in a very large number of frequent jumps. Frequent jumps are a problem for several reasons, including reduced duty cycles for writing and reading, increased mechanical noise and reduced operational lifetimes.
During a jump, it is impossible to either write to the disk medium or read from the disk medium. Consequently there is mush less time available for writing and reading, and accordingly, the duty cycle for writing and reading can be significantly reduced. As a result, the writing and reading rates must be significantly increased, perhaps even greater than the capacity of the player/recorder. In a 1× machine as described above, the maximum data rates available are approximately 5 megabits/second for playing back (reading) and 5 megabits/second for recording. Such rates are only half the minimum rate of a machine of minimal capability, and accordingly, apparently simultaneous playing back and recording with such a machine would seem to be impossible, particularly for multiple pauses.
Frequent jumps generate a lot of audible noise, such as is often heard in computer hard drives. Such noise can be particularly annoying, for example while viewing an HDTV movie with surround sound.
Frequent jumps also prematurely wear out the pickup assembly.
Managing multiple pauses is also much more difficult than managing single pauses. It should be appreciated that a user command to initiate a second pause can occur not only during the midst of the program, but will occur during the course of a continuous simultaneous record/playback sequence resulting from the first pause. Accordingly, it is desirable to provide novel features that can enable second and further pauses to be implemented, and further, to enable such features within the constraints of the maximum available data rates.